Mixed Metal Oxide Ammoxidation Catalysts

ABSTRACT

Olefins selected from the group consisting of propylene, isobutylene or mixtures thereof, are converted to acrylonitrile, methacrylonitrile, and mixtures thereof in a process comprising reacting in the vapor phase at an elevated temperature and pressure said olefin with a molecular oxygen containing gas and ammonia in the presence of a catalytic composition comprising a complex of metal oxides comprising bismuth, molybdenum, iron, cerium and other promoter elements, wherein the X-ray diffraction pattern of the catalytic composition has X-ray diffraction peaks at 2θ angle 28±0.3 degrees and 2θ angle 26.5±0.3 degrees, and wherein the ratio of the intensity of the most intense x-ray diffraction peak within 2θ angle 28±0.3 degrees to the intensity of most intense x-ray diffraction peak within 2θ angle 26.5±0.3 degrees is defined as X/Y, and wherein X/Y is greater than or equal to 0.7.

REFERENCE TO RELATED APPLICATIONS

This application is related to (i) U.S. patent application Ser. No.______, entitled “Process for Preparing Improved Mixed Metal OxideAmmoxidation Catalysts”, filed Mar. 23, 2010, by Brazdil et al. underAttorney Docket No. 50031, and (ii) U.S. patent application Ser. No.______, entitled “Attrition Resistance Mixed Metal Oxide Catalysts”,filed Mar. 23, 2010, by Brazdil et al. under Attorney Docket No. 50047,both filed on the date even herewith, which are hereby incorporated byreference for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved catalyst for use in theammoxidation of an unsaturated hydrocarbon to the correspondingunsaturated nitrile. In particular, the present invention is directed toan improved catalytic composition for the ammoxidation of propyleneand/or isobutylene to acrylonitrile and/or methacrylonitrile,respectively.

2. Description of the Prior Art

Catalysts containing oxides of iron, bismuth and molybdenum, promotedwith suitable elements, have long been used for the conversion ofpropylene and/or isobutylene at elevated temperatures in the presence ofammonia and oxygen (usually in the form of air) to manufactureacrylonitrile and/or methacrylonitrile. In particular, Great BritainPatent 1436475; U.S. Pat. Nos. 4,766,232; 4,377,534; 4,040,978;4,168,246; 5,223,469 and 4,863,891 are each directed tobismuth-molybdenum-iron catalysts which may be promoted with the GroupII elements to produce acrylonitrile. In addition, U.S. Pat. Nos.5,093,299, 5212,137, 5,658,842 and 5,834,394 are directed tobismuth-molybdenum promoted catalysts exhibiting high yields toacrylonitrile.

In part, the instant invention relates to an improvedbismuth-molybdenum-iron catalysts. Typically, such catalysts areproduced in a batch process by simply combining and reacting, sourcecompounds for the various metal components. However, more complex andmultiple-step preparations have been used. For example, U.S. Pat. No.4,040,978 taught a process for catalyst preparation where molybdates ofeach metal were separately made and then combined and reacted; and U.S.Pat. No. 4,148,757 taught a process for catalyst preparation wherebismuth and molybdenum were first reacted to form a bismuth molybdateand then the bismuth molybdate was combined with a mixture of sourcecompounds for the various other metal components.

SUMMARY OF THE INVENTION

The present invention is directed to an improved mixed metal oxidecatalyst for the ammoxidation of propylene and/or isobutylene. Thisimproved catalyst, as described herein, provides greater overallconversion for the ammoxidation of the propylene and/or isobutylene tonitriles (i.e. compounds having the function group “—CN”, such asacrylonitrile, methacrylonitrile, acetonitrile and hydrogen cyanide).

In one embodiment, the invention is directed to a catalytic compositionwherein the relative ratios of the elements in said composition arerepresented by the following formula:

Mo₁₂Bi_(a)Fe_(b)A_(c)D_(d)E_(e)F_(f)G_(g)Ce_(h)O_(x)

wherein

-   -   A is at least one element selected from the group consisting of        sodium, potassium, rubidium and cesium; and    -   D is at least one element selected from the group consisting of        nickel, cobalt, manganese, zinc, magnesium, calcium, strontium,        cadmium and barium;    -   E is at least one element selected from the group consisting of        chromium, tungsten, boron, aluminum, gallium, indium,        phosphorus, arsenic, antimony, vanadium and tellurium;    -   F is at least one element selected from the group consisting of        a rare earth element, titanium, zirconium, hafnium, niobium,        tantalum, thallium, silicon, germanium, and lead;    -   G is at least one element selected from the group consisting of        silver, gold, ruthenium, rhodium, palladium, osmium, iridium,        platinum and mercury; and        a, b, c, d, e, f, g, h and n are, respectively, the atomic        ratios of bismuth (Bi), iron (Fe), A, D, E, F, cerium (Ce) and        oxygen (O), relative to 12 atoms of molybdenum (Mo), wherein    -   a is from 0.05 to 7,    -   b is from 0.1 to 7,    -   c is from 0.01 to 5,    -   d is from 0.1 to 12,    -   e is from 0 to 5,    -   f is from 0 to 5,    -   g is from 0 to 0.2,    -   h is from 0.01 to 5, and    -   n is the number of oxygen atoms required to satisfy the valence        requirements of the other component elements present;        wherein 0.15≦(a+h)/d≦1 and 0.8≦h/b≦5, and        wherein the X-ray diffraction pattern of the above identified        catalytic composition has X-ray diffraction peaks at 2θ angle        28±0.3 degrees and 2θ angle 26.5±0.3 degrees, and wherein the        ratio of the intensity of the most intense x-ray diffraction        peak within 2θ angle 28±0.3 degrees to the intensity of most        intense x-ray diffraction peak within 2θ angle 26.5±0.3 degrees        is defined as X/Y, and wherein X/Y is greater than or equal to        0.7.

The present invention is also directed to processes for the conversionof an olefin selected from the group consisting of propylene andisobutylene or mixtures thereof, to acrylonitrile, and/ormethacrylonitrile, and other by-product nitriles (i.e. compounds havingthe function group “—CN”, such acetonitrile and hydrogen cyanide) andmixtures thereof, by reacting in the vapor phase at an elevatedtemperature and pressure said olefin with a molecular oxygen containinggas and ammonia in the presence of an mixed metal oxide catalyst asdescribed in the previous paragraph.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of the historical trend with respect to acrylonitrilecatalyst development showing Acrylonitrile Yield on the x-axis andHydrogen Cyanide Yield on the y-axis. This plot illustrates that overtime as Acrylonitrile Yield has been improved, the correspondingHydrogen Cyanide Yield has decreased. The catalysts of the instantinvention do not conform to this historical trend. The catalysts of theinstant invention provide an increase in Acrylonitrile Yield without asignificant decrease in Hydrogen Cyanide Yield as found in thehistorical trend.

FIG. 2 is an XRD diffraction pattern or XRD diffractogram of a catalystwithin the scope of the instant invention. This diffractogramillustrates an intense x-ray diffraction peak within 2θ angle 28±0.3degrees (with the intensity defined as “X”) and an intense x-raydiffraction peak within 2θ angle 26.5±0.3 degrees (with the intensitydefined as “Y”). The ratio of X/Y is 0.97.

FIG. 3 is a plot of attrition resistance versus the Ce/Fe ratio in thecatalyst. It has been discovered that catalysts having the compositionsdescribed herein and having a Ce/Fe ratio greater than or equal to 0.8and less than or equal to 5 tend to be stronger in that they have alower attrition loss as determined by a submerged jet attrition test.

DETAILED DESCRIPTION OF THE INVENTION

The instant invention is a novel catalyst comprising a uniquecombination and ratio of promoters offering better performance in thecatalytic ammoxidation of propylene, isobutylene or mixtures thereof, toacrylonitrile, methacrylonitrile and mixtures thereof, respectively

The Catalyst:

The present invention is directed to a multi-component mixed metal oxideammoxidation catalytic composition comprising a complex of catalyticoxides wherein the elements and the relative ratios of the elements insaid catalytic composition are represented by the following formula:

Mo₁₂Bi_(a)Fe_(b)A_(c)D_(d)E_(e)F_(f)G_(g)Ce_(h)O_(x)

wherein

-   -   A is at least one element selected from the group consisting of        sodium, potassium, rubidium and cesium; and    -   D is at least one element selected from the group consisting of        nickel, cobalt, manganese, zinc, magnesium, calcium, strontium,        cadmium and barium;    -   E is at least one element selected from the group consisting of        chromium, tungsten, boron, aluminum, gallium, indium,        phosphorus, arsenic, antimony, vanadium and tellurium;    -   F is at least one element selected from the group consisting of        a rare earth element, titanium, zirconium, hafnium, niobium,        tantalum, thallium, silicon, germanium, and lead;    -   G is at least one element selected from the group consisting of        silver, gold, ruthenium, rhodium, palladium, osmium, iridium,        platinum and mercury; and        a, b, c, d, e, f, g, h and n are, respectively, the atomic        ratios of bismuth (Bi), iron (Fe), A, D, E, F, cerium (Ce) and        oxygen (O), relative to 12 atoms of molybdenum (Mo), wherein    -   a is from 0.05 to 7,    -   b is from 0.1 to 7,    -   c is from 0.01 to 5,    -   d is from 0.1 to 12,    -   e is from 0 to 5,    -   f is from 0 to 5,    -   g is from 0 to 0.2,    -   h is from 0.01 to 5, and    -   n is the number of oxygen atoms required to satisfy the valence        requirements of the other component elements present.

In one embodiment of the above described catalytic composition,0.15≦(a+h)/d≦1. In another embodiment of the above described catalyticcomposition, 0.8≦h/b≦5. In yet another embodiment, the X-ray diffractionpattern of the above identified catalytic composition has X-raydiffraction peaks at 2θ angle 28±0.3 degrees and 2θ angle 26.5±0.3degrees and if the ratio of the intensity of the most intense x-raydiffraction peak within 2θ angle 28±0.3 degrees to the intensity of mostintense x-ray diffraction peak within 2θ angle 26.5±0.3 degrees isdefined as X/Y, then X/Y is greater than or equal to 0.7. In otherindependent embodiments of the above identified catalytic composition:0.2≦(a+h)/d≦0.6; 0.3≦(a+h)/d≦0.5; 1≦h/b≦3; 1.5≦h/b≦2; X/Y is greaterthan or equal to 0.8; and/or X/Y is greater than or equal to 0.90.

In the embodiment, (where 0.8≦h/b≦5), “h/b” represents the ratio ofcerium to iron in the catalyst and for any catalyst formulation thisratio is simply the moles of cerium (as represented by the subscript forcerium in the formula) divided by the moles of iron (as represented bythe subscript for iron in the formula). It has been discovered thatcatalysts described by the above formula wherein 0.8≦h/b≦5 tend to bestronger in that they have a lower attrition loss as determined by asubmerged jet attrition test.

In the embodiment, characterized by the X-ray diffraction pattern of theabove identified catalytic composition having X-ray diffraction peaks at2θ angle 28±0.3 degrees and 2θ angle 26.5±0.3 degrees and if the ratioof the intensity of the most intense x-ray diffraction peak within 2θangle 28±0.3 degrees to the intensity of most intense x-ray diffractionpeak within 2θ angle 26.5±0.3 degrees is defined as X/Y, then X/Y isgreater than or equal to 0.7, it has been discovered that such catalystsprovide greater overall conversion for the ammoxidation of propyleneand/or isobutylene to nitriles (i.e. compounds having the function group“—CN”, such as acrylonitrile, methacrylonitrile, acetonitrile andhydrogen cyanide

As used herein, “catalytic composition” and “catalyst” are synonymousand used interchangeably. As used herein, a “rare earth element” meansat least one of lanthanum, cerium, praseodymium, neodymium, promethium,samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium,thulium, ytterbium, scandium and yttrium. As used herein, “2θ” issynomonous with “2 theta”.

The catalyst of the present invention may be used either supported orunsupported (i.e. the catalyst may comprise a support). Suitablesupports are silica, alumina, zirconium, titania, or mixtures thereof. Asupport typically serves as a binder for the catalyst and results in astronger (i.e. more attrition resistant) catalyst. However, forcommercial applications, an appropriate blend of both the active phase(i.e. the complex of catalytic oxides described above) and the supportis crucial to obtain an acceptable activity and hardness (attritionresistance) for the catalyst. Typically, the support comprises between40 and 60 weight percent of the supported catalyst. In one embodiment ofthis invention, the support may comprise as little as about 30 weightpercent of the supported catalyst. In another embodiment of thisinvention, the support may comprise as much as about 70 weight percentof the supported catalyst.

In one embodiment the catalyst is supported using a silica sol.Typically, silica sols contain some sodium. In one embodiment, thesilica sol contains less than 600 ppm sodium. In another embodiment, thesilica sol contains less than 200 ppm sodium. Typically, the averagecolloidal particle diameter of the silica sol is between about 15 nm andabout 50 nm. In one embodiment of this invention, the average colloidalparticle diameter of the silica sol is about 10 nm and can be as low asabout 4 nm. In another embodiment of this invention, the averagecolloidal particle diameter of the silica sol is about 100 nm. Inanother embodiment of this invention, the average colloidal particlediameter of the silica sol is about 20 nm.

Catalyst Preparation:

In one embodiment, the elements in the above identified catalystcomposition are combined together in an aqueous catalyst precursorslurry, the aqueous precursor slurry so obtained is dried to form acatalyst precursor, and the catalyst precursor is calcined to form thecatalyst. However, unique to the process of the instant invention is thefollowing:

(i) combining, in an aqueous solution, source compounds of Bi and Ce,and optionally one or more of Na, K, Rb, Cs, Ca, a rare earth element,Pb, W and Y, to form a mixture (i.e. a first mixture),

(ii) adding a source compound of molybdenum to the mixture (i.e. thefirst mixture) to react with the mixture and form a precipitate slurry,and

(iii) combining the precipitate slurry with source compounds of theremaining elements and of the remaining molybdenum in the catalyst toform the aqueous catalyst precursor slurry.

As used herein, “source compounds” are compounds which contain and/orprovide one or more of the metals for the mixed metal oxide catalystcomposition. As used herein, “remaining elements” or “remaining elementsin the catalyst” refers to those elements and the quantity of thoseelements represented by “A”, “D”, “E”, “F” and “G” in the above formulawhich were not included in the first mixture. In one embodiment, someelements may be a part of both the first and second mixture. Further, asused herein, “remaining molybdenum” or “remaining molybdenum in thecatalyst” refers to that quantity of molybdenum required in the finishedcatalyst which was not present (i.e. not included in the preparation of)in the precipitate slurry. Lastly, the sum of the quantities ofmolybdenum provided in the source compounds of molybdenum added in (ii)and (iii) is equal to the total quantity of molybdenum present in thecatalyst.

In the catalyst preparation described herein, the source compounds ofthe remaining elements and of the remaining molybdenum which arecombined with the precipitate slurry may be combined in any order orcombination of such remaining elements and remaining molybdenum. In oneembodiment, a mixture of the source compounds of the remaining elementsand of the remaining molybdenum is combined with the precipitate slurryto form the aqueous catalyst precursor slurry. In another embodiment,(i) a mixture of the source compounds of the remaining elements iscombined with the precipitate slurry, and (ii) source compounds of theremaining molybdenum are separately added to the precipitate slurry toform the aqueous catalyst precursor slurry. The order of addition is notcritical. In another embodiment, source compounds of the remainingelements and of the remaining molybdenum are added individually (i.e.one at a time) to the precipitate slurry. In another embodiment,multiple (i.e. more than one) mixtures of source compounds of theremaining elements and of the remaining molybdenum, wherein each mixturecontains one or more of the source compounds of the remaining elementsor of the remaining molybdenum, are separately added (i.e. one mixtureat a time or multiple mixtures added simultaneously) to the precipitateslurry to form the aqueous catalyst precursor slurry. In yet anotherembodiment, a mixture of source compounds of the remaining elements iscombined with a source compound of molybdenum and the resulting mixtureis then added to the precipitate slurry to form the catalyst precursorslurry. In yet another embodiment, the support is silica (SiO₂) and thesilica is combined with a source compound for the remaining molybdenumprior to combining the remaining molybdenum with the precipitate slurry(i.e. the silica and a source compound for the remaining molybdenum arecombined to form a mixture and then this mixture is added to theprecipitate slurry, individually or in combination with one or moresource compounds of the remaining elements).

In the catalyst preparation described herein, molybdenum is added bothin the preparation of the precipitate slurry and in the preparation ofthe aqueous catalyst precursor slurry. On an atomic level, the minimumamount of molybdenum added to form the precipitate slurry is determinedby the following relationship

Mo=1.5(Bi+Ce)+0.5(Rb+Na+K+Cs)+(Ca)+1.5(sum of the number of atoms ofrare earth elements)+(Pb)+3(W)+1.5(Y)

Wherein in the above relationship “Mo” is the number of atoms ofmolybdenum to be added to the first mixture, and “Bi”, “Ce”, “Rb”, “Na”,“K”, “Cs”, “Ca”, “Pb”, “W” and “Y” is the number of atoms of bismuth,cerium, rubidium, sodium, potassium, cesium, calcium, lead, tungsten andyttrium, respectively, present in the first mixture.

Typically, the amount of molybdenum added to the first mixture to formthe precipitate slurry is about 20 to 35% of the total molybdenum in thefinal catalyst. In one embodiment, a source compound for the remainingmolybdenum present in the catalyst is added to the mixture of the sourcecompounds of the remaining elements (i.e. the second mixture) prior tothe combination of the mixture of the remaining elements with theprecipitate slurry to form the catalyst precursor slurry. In otherembodiments, a source compound of molybdenum containing the remainingmolybdenum present in the catalyst is added to the precipitate slurryeither prior to, after or simultaneously with, the mixture of the sourcecompounds of the remaining elements (i.e. the second mixture) in orderto form the catalyst precursor slurry.

In the instant preparation, source compounds of Bi and Ce, andoptionally one or more of Na, K, Rb, Cs, Ca, a rare earth element, Pb, Wand Y, are combined in an aqueous solution to form a mixture. In oneembodiment, bismuth nitrate and optionally other metal nitrates (i.e.nitrates of Na, K, Rb, Cs, Ca, a rare earth element, Pb, W and/or Y) aredissolved in an aqueous solution of eerie ammonium nitrate.

Added to the mixture comprising the bismuth and cerium (and optionallyone or more of Na, K, Rb, Cs, Ca, a rare earth element, Pb, W and Y) isa source compound of molybdenum. In one embodiment this source compoundof molybdenum is ammonium heptamolybdate dissolved in water. Upon theaddition of the molybdenum source compound to the mixture comprising thebismuth and cerium, a reaction will occur which will result in aprecipitate and the resulting mixture is the precipitate slurry.

The precipitate slurry is then combined with a mixture of sourcecompound of the remaining elements of the catalyst and a source compoundof molybdenum, to form the aqueous catalyst precursor slurry. Themixture of source compounds of the remaining elements and a sourcecompound of molybdenum may be prepared by combining source compounds ofthe remaining elements in an aqueous solution (e.g. source compounds arecombined in water) and then adding a source compound of molybdenum. Inone embodiment this source compound of molybdenum is ammoniumheptamolybdate dissolved in water. When combining the precipitate slurrywith the remaining elements/molybdenum mixture, the order of addition isnot important, i.e. the precipitate slurry may be added to the remainingelements/molybdenum mixture or the remaining elements/molybdenum mixturemay be added to the precipitate slurry. The aqueous catalyst precursorslurry is maintained at an elevated temperature.

The amount of aqueous solvent in each of the above described aqueousmixtures and slurries may vary due to the solubilities of the sourcecompounds combined to form the particular mixed metal oxide. The amountof aqueous solvent should at least be sufficient to yield a slurry ormixture of solids and liquids which is able to be stirred.

In any case, the source compounds are preferably combined and/or reactedby a protocol that comprises mixing the source compounds during thecombination and/or reaction step. The particular mixing mechanism is notcritical, and can include for example, mixing (e.g., stirring oragitating) the components during the reaction by any effective method.Such methods include, for example, agitating the contents of the vessel,for example by shaking, tumbling or oscillating the component-containingvessel. Such methods also include, for example, stirring by using astirring member located at least partially within the reaction vesseland a driving force coupled to the stirring member or to the reactionvessel to provide relative motion between the stirring member and thereaction vessel. The stirring member can be a shaft-driven and/orshaft-supported stirring member. The driving force can be directlycoupled to the stirring member or can be indirectly coupled to thestirring member (e.g., via magnetic coupling). The mixing is generallypreferably sufficient to mix the components to allow for efficientreaction between components of the reaction medium to form a morehomogeneous reaction medium (e.g., and resulting in a more homogeneousmixed metal oxide precursor) as compared to an unmixed reaction. Thisresults in more efficient consumption of starting materials and in amore uniform mixed metal oxide product. Mixing the precipitate slurryduring the reaction step also causes the precipitate to form in solutionrather than on the sides of the reaction vessel. More advantageously,having the precipitate form in solution allows for particle growth onall faces of the particle rather than the limited exposed faces when thegrowth occurs out from the reaction vessel wall.

A source compound of molybdenum may include molybdenum (VI) oxide(MoO₃), ammonium heptamolybdate or molybdic acid. The source compound ofmolybdenum may be introduced from any molybdenum oxide such as dioxide,trioxide, pentoxide or heptaoxide. However, it is preferred that ahydrolyzable or decomposable molybdenum salt be utilized as sourcecompound of molybdenum.

Typical source compounds for bismuth, cerium and the remaining elementsof the catalyst are nitrate salts of the metals. Such nitrate salts arereadily available and easily soluble. A source compound of bismuth mayinclude an oxide or a salt which upon calcination will yield the oxide.The water soluble salts which are easily dispersed but form stableoxides upon heat treating are preferred. In one embodiment the sourcecompound of bismuth is bismuth nitrate, Bi(NO₃)₃.5H₂O

A source compound of cerium may include an oxide or a salt which uponcalcination will yield the oxide. The water soluble salts which areeasily dispersed but form stable oxides upon heat treating arepreferred. In one embodiment the source compound of cerium is cericammonium nitrate, (NH₄)₂Ce(NO₃)₆.

A source compound of iron may be obtained from any compound of ironwhich, upon calcination will result in the oxide. As with the otherelements, water soluble salts are preferred for the ease with which theymay be uniformly dispersed within the catalyst. Most preferred is ferricnitrate.

Source compounds for the remaining elements may be derived from anysuitable source. For example, cobalt, nickel and magnesium may beintroduced into the catalyst using nitrate salts. Additionally,magnesium may be introduced into the catalyst as an insoluble carbonateor hydroxide which upon heat treating results in an oxide. Phosphorusmay be introduced in the catalyst as an alkaline metal salt or alkalineearth metal salt or the ammonium salt but is preferably introduced asphosphoric acid.

Source compounds for the alkali components of the catalyst may beintroduced into the catalyst as an oxide or as a salt which uponcalcination will yield the oxide.

-   -   Solvents, in addition to water, may be used to prepare the mixed        metal oxides according to the invention include, but are not        limited to, alcohols such as methanol, ethanol, propanol, diols        (e.g. ethylene glycol, propylene glycol, etc.), organic acids        such as acetic acid, as well as other polar solvents known in        the art. The metal source compounds are at least partially        soluble in the solvent.    -   As previously noted, the catalyst of the present invention may        be used either supported or unsupported (i.e. the catalyst may        comprise a support). Suitable supports are silica, alumina,        zirconium, titania, or mixtures thereof. The point of addition        of the support is not critical in the preparation of the        catalyst. The support may be added anytime prior to the catalyst        precursor slurry being dried. The support may be added at any        time during or after the preparation of any mixture of elements,        the precipitate slurry or the catalyst precursor slurry. Further        the support need not be added in a single point or step (i.e.        the support may be added at multiple points in the preparation.        In one embodiment, the support is combined with the other        ingredients during the preparation of the aqueous catalyst        precursor slurry. In one embodiment, the support is added to the        precipitate slurry (i.e. after the precipitate slurry is        prepared). In one embodiment, the support is combined with the        source compound of molybdenum prior to combining the source        compound of molybdenum with source compounds of the remaining        elements in the catalyst to form the “second mixture” referred        to above.

The catalyst precursor slurry is dried and denitrified (i.e. the removalof nitrates) to yield the catalyst precursor. Preferably the catalystprecursor slurry is spray-dried at a temperature of between 110° C. and350° C. dryer outlet temperature, preferably between 110° C. and 250°C., most preferably between 110° C. and 180° C. The denitrificationtemperature may range from 100° C. to 500° C., preferably 250° C. to450° C.

Finally, the dried catalyst precursor is calcined. In one embodiment,the calcination is effected in air. In another embodiment, thecalcination is effected in an inert atmosphere, such as nitrogen.Preferred calcination conditions include temperatures ranging from about300° C. to about 700° C., more preferably from about 350° C. to about650° C., and in some embodiments, the calcination may be at about 600°C.

The catalysts of the present invention may be prepared by any of thenumerous methods of catalyst preparation which are known to those ofskill in the art. In one embodiment, the catalyst components may bemixed with a support in the form of the slurry followed by drying or thecatalyst components may be impregnated on silica or other supports.

Ammoxidation Process:

The catalysts of the instant invention are useful in ammoxidationprocesses for the conversion of an olefin selected from the groupconsisting of propylene, isobutylene or mixtures thereof, toacrylonitrile, methacrylonitrile and mixtures thereof, respectively, byreacting in the vapor phase at an elevated temperature and pressure saidolefin with a molecular oxygen containing gas and ammonia in thepresence of the catalyst. The catalysts of the instant invention arealso useful for the ammoxidation of methanol to hydrogen cyanide and theammoxidation of ethanol to acetonitrile. In one embodiment employing thecatalysts described herein, methanol and/or ethanol can be co-fed to aprocess for the ammoxidation of propylene, isobutylene or mixturesthereof to acrylonitrile, methacrylonitrile or mixtures thereof, inorder to increase the production of hydrogen cyanide and/or acetonitrileco-products resulting from such process.

Preferably, the ammoxidation reaction is performed in a fluid bedreactor although other types of reactors such as transport line reactorsare envisioned. Fluid bed reactors, for the manufacture of acrylonitrileare well known in the prior art. For example, the reactor design setforth in U.S. Pat. No. 3,230,246, herein incorporated by reference, issuitable.

Conditions for the ammoxidation reaction to occur are also well known inthe prior art as evidenced by U.S. Pat. Nos. 5,093,299; 4,863,891;4,767,878 and 4,503,001; herein incorporated by reference. Typically,the ammoxidation process is performed by contacting propylene orisobutylene in the presence of ammonia and oxygen with a fluid bedcatalyst at an elevated temperature to produce the acrylonitrile ormethacrylonitrile. Any source of oxygen may be employed. For economicreasons, however, it is preferred to use air. The typical molar ratio ofthe oxygen to olefin in the feed should range from 0.5:1 to 4:1,preferably from 1:1 to 3:1.

The molar ratio of ammonia to olefin in the feed in the reaction mayvary from between 0.5:1 to 2:1. There is really no upper limit for theammonia-olefin ratio, but there is generally no reason to exceed a ratioof 2:1 for economic reasons. Suitable feed ratios for use with thecatalyst of the instant invention for the production of acrylonitrilefrom propylene are an ammonia to propylene ratio in the range of 0.9:1to 1.3:1, and air to propylene ratio of 8.0:1 to 12.0:1. The catalyst ofthe instant invention is able to provide high yields of acrylonitrile atrelatively low ammonia to propylene feed ratios of about 1:1 to about1.05:1. These “low ammonia conditions” help to reduce unreacted ammoniain the reactor effluent, a condition known as “ammonia breakthrough”,which subsequently helps to reduce process wastes. Specifically,unreacted ammonia must be removed from the reactor effluent prior to therecovery of the acrylonitrile. Unreacted ammonia is typically removed bycontacting the reactor effluent with sulfuric acid to yield ammoniumsulfate or by contacting the reactor effluent with acrylic acid to yieldammonium acrylate, which in both cases results in a process waste streamto be treated and/or disposed.

The reaction is carried out at a temperature of between the ranges ofabout 260° to 600° C., preferred ranges being 310° to 500° C.,especially preferred being 350° to 480° C. The contact time, althoughnot critical, is generally in the range of 0.1 to 50 seconds, withpreference being to a contact time of 1 to 15 seconds.

The products of reaction may be recovered and purified by any of themethods known to those skilled in the art. One such method involvesscrubbing the effluent gases from the reactor with cold water or anappropriate solvent to remove the products of the reaction and thenpurifying the reaction product by distillation.

The primary utility of the catalyst prepared by the process of theinstant invention is for the ammoxidation of propylene to acrylonitrile.Other utilities include the ammoxidation of propane to acrylonitrile andthe ammoxidation of ethanol to acetonitrile. The catalyst prepared bythe process of the instant invention may also be used for the oxidationof propylene to acrylic acid. Such processes are typically two stageprocesses, wherein propylene is converted in the presence of a catalystto primarily acrolein in the first stage and the acrolein is convertedin the presence of a catalyst to primarily acrylic acid in the secondstage. The catalyst described herein is suitable for use in the firststage for the oxidation of propylene to acrolein.

SPECIFIC EMBODIMENTS

In order to illustrate the instant invention, catalyst prepared inaccordance with the instant invention were evaluated and compared undersimilar reaction conditions to similar catalysts prepared by prior artmethods outside the scope of the instant invention. These examples areprovided for illustrative purposes only.

Catalysts having the composition ofCs_(0.1)K_(0.1)Ni₅Mg₂Na_(0.05)Fe_(1.8)Bi_(0.45)Ce_(1.1)Mo_(12.55)O_(50.35)+45wt % SiO₂ were prepared by various preparation methods as describedbelow and tested in a bench scale reactor for the ammoxidation ofpropylene to acrylonitrile. All testing was conducted in a 40 cc fluidbed reactor. Propylene was feed into the reactor at a rate of 0.06 WWH(i.e. weight of propylene/weight of catalyst/hour). Pressure inside thereactor was maintained at 10 psig. Reaction temperature was 430° C.After a stabilization period of ˜20 hours or more, samples of reactionproducts were collected. Reactor effluent was collected in bubble-typescrubbers containing cold HCl solution. Off-gas rate was measured withsoap film meter, and the off-gas composition was determined at the endof the run with the aid of gas chromatograph fitted with a split columngas analyzer. At the end of the recovery run, the entire scrubber liquidwas diluted to approximately 200 gms with distilled water. A weightedamount of 2-butanone was used as internal standard in a ˜50 gram aliquotof the dilute solution. A 2 μl sample was analyzed in a GC fitted with aflame ionization detector and a Carbowax column. The amount of NH₃ wasdetermined by titrating the free HCl excess with NaOH solution.

Comparative Example C1 Conventional Method

Reaction mixture A was prepared by heating 224 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (203.75 g) to form a clear colorless solution. Silica sol(625 g, 32.5 wt % silica) was then added with stirring.Reaction mixture B was prepared by heating 30 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (66.9 g),Ni(NO₃)₂.6H₂0(133.7 g), Mg(NO₃)₂.6H₂O (47.2 g), Bi(NO₃)₃.5H₂O (20.1 g),CsNO₃ (1.79 g), KNO₃ (0.93 g), and NaNO₃ (0.39 g). Next, 110.0 g of 50wt % aqueous (NH₄)₂Ce(NO₃)₆ solution was added with stirring.Reaction mixture B was then added to reaction mixture A with stirring tofrom the catalyst precursor slurry. The catalyst precursor slurry wasallowed to stir for one hour while it cooled to approximately 40° C. Itwas then homogenized in a blender for 3 minutes at 5000 rpm. The slurrywas then spray dried in a spray dryer at an inlet/outlet temperature of325/140° C. The resulting powder was denitrified by heat treating for 3hours in air at 290° C., followed by an additional 3 hours at 425° C.The powder was then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst in a 40 cc microreactor. Testing results are shown in Table 1.

Comparative Example C2 Prepared According to U.S. Pat. No. 4,212,766i.e. no Bi—Ce—Mo Precipitate Slurry Formed as a Separate Step

Reaction mixture A was prepared by heating 233 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (212.1 g) to form a clear colorless solution. Silica sol(692 g, 32.5 wt % silica) was then added with stirring.Reaction mixture B was prepared by heating 33 ml of deionized water to55° C. and then adding sequentially with stirring Fe(NO₃)₃.9H₂O (73.6g), Ni(NO₃)₂.6H₂O (147.1 g), Mg(NO₃)₂.6H₂O (51.9 g), CsNO₃ (1.97 g),KNO₃ (1.02 g), NaNO₃ (0.43 g), and 122.0 g of 50 wt % aqueous(NH₄)₂Ce(NO₃)₆ solution.Reaction mixture C was prepared by heating 152 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (12.1 g) to form a clear colorless solution.Reaction mixture D was prepared by dissolving Bi(NO₃)₃.5H₂O (22.1 g) in160 g of 10 wt % aqueous HNO₃ solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture D to reactionmixture C. This resulted in precipitation of a colorless solid. Stirringwas continued for 15 minutes while the temperature was maintained in the50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating for 3 hours in air at 290° C., followed byan additional 3 hours at 425° C. The powder was then calcined in air at560° C. for 3 hours. The resulting calcined powder was then tested as apropylene ammoxidation catalyst in a 40 cc microreactor. Testing resultsare shown in Table 1.

Example 1 Prepared in Accordance with the Invention

Reaction mixture A was prepared by heating 198 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (180.4 g) to form a clear colorless solution. Silica sol(692 g, 32.5 wt % silica) was then added with stirring.Reaction mixture B was prepared by heating 33 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (73.6 g),Ni(NO₃)₂.6H₂O (147.1 g), and Mg(NO₃)₂.6H₂O (51.9 g).Reaction mixture C was prepared by heating 48 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (43.75 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 122.0 g of 50 wt %aqueous (NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii) while the solutionwas stirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (22.1 g),CsNO₃ (1.97 g), KNO₃ (1.02 g), and NaNO₃ (0.43 g), resulting in a clearorange solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This to resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry. Stirring of Reactionmixture F was continued for 15 minutes while the temperature wasmaintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating for 3 hours in air at 290° C., followed byan additional 3 hours at 425° C. The powder was then calcined in air at560° C. for 3 hours. The resulting calcined powder was then tested as apropylene ammoxidation catalyst in a 40 cc microreactor. Testing resultsare shown in Table 1.

Example 2 Prepared in Accordance with the Invention

Reaction mixture A was prepared by heating 198 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (180.4 g) to form a clear colorless solution.Reaction mixture B was prepared by heating 33 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (73.6 g),Ni(NO₃)₂.6H₂0 (147.1 g), and Mg(NO₃)₂.6H₂O (51.9 g).Reaction mixture C was prepared by heating 48 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (43.75 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 122.0 g of 50 wt %aqueous (NH₄)₂Ce(NO₃)₆ solution to 55° C., (ii) while the solution wasstirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (22.1 g), CsNO₃(1.97 g), KNO₃ (1.02 g), and NaNO₃ (0.43 g), resulting in a clear orangesolution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by (i) adding reaction mixture C toreaction mixture D, which resulted in precipitation of an orange solid(this resulting mixture was the precipitate slurry), (ii) stirring ofthe precipitate slurry was continued for 15 minutes while thetemperature was maintained in the 50-55° C. range, and (iii) adding withstirring silica sol (692 g, 32.5 wt % silica).Reaction mixture E was then added to reaction mixture F to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating for 3 hours in air at 290° C., followed byan additional 3 hours at 425° C. The powder was then calcined in air at560° C. for 3 hours. The resulting calcined powder was then tested as apropylene ammoxidation catalyst in a 40 cc microreactor. Testing resultsare shown in Table 1.

Comparative Example 3 C-49MC Acrylonitrile Catalyst

Testing results and other data are shown in Tables 2 for C-49MCAcrylonitrile Catalyst. “Catalyst C-49MC” is the product designation forcommercial catalyst manufactured and sold by INEOS USA LLC. Thecomposition of Catalyst C-49MC is a trade secret of INEOS USA LLC.“C-49MC” is a trademark of INEOS USA LLC.

Comparative Example C4Ni_(7.5)Mg₃Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(15.85) ^(O)_(63.835)+50 wt % 27 ppm Na, 39 nm SiO₂

Reaction mixture A was prepared by heating 225.1 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (204.6 g) to form a clear colorless solution. Silica sol(27 ppm Na, 39 nm avg. particle size, 595.2 g, 42 wt % silica) was thenadded with stirring.Reaction mixture B was prepared by heating 32.2 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (53.2 g),Ni(NO₃)₂.6H₂0 (159.5 g), Mg(NO₃)₂.6H₂O (56.2 g), Bi(NO₃)₃.5H₂O (16 g),Cr(NO₃)₃.9H₂0 (2.9 g) and RbNO₃ (1.3 g).88.2 g of 50 wt % aqueous (NH₄)₂Ce(NO₃)₆ solution was added to solutionB followed by adding this resulting mixture to solution A with mixing at˜55° C. for one hour followed by cooling to 40° C. The resultingcatalyst slurry was then homogenized in a blender for 3 minutes at 5000rpm. The slurry was then spray dried in a spray dryer at an inlet/outlettemperature of 325/140° C. The resulting powder was denitrified by heattreating 3 hours in air at 290° C., 3 hours in air at 425° C. and thencalcined in air at 560° C. for 3 hours. The resulting calcined powderwas then tested as a propylene ammoxidation catalyst. Testing resultsare shown in Table 2.

Comparative Example C5Ni_(7.5)Mg₃Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(15.85) ^(O)_(63.835)+50 wt % SiO₂

Reaction mixture A was prepared by heating 191.1 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (173.8 g) to form a clear colorless solution. Silica sol(27 ppm Na, 39 nm avg. particle size, 595.2 g, 42 wt % silica) was thenadded with stirring.Reaction mixture B was prepared by heating 32.1 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (53.2 g),Ni(NO₃)₂.6H₂0 (159.5 g), Mg(NO₃)₂.6H₂O (56.2 g) and Cr(NO₃)₃.9H₂0 (2.9g).Reaction mixture C was prepared by heating 33.9 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (30.8 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 88.2 g of 50 wt % aqueous(NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii) while the solution wasstirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (16 g) and RbNO₃(1.3 g) resulting in a clear orange solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry. Stirring of Reactionmixture F was continued for 15 minutes while the temperature wasmaintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture F to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating 3 hours in air at 290° C., 3 hours in airat 425° C. and then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst. Testing results are shown in Table 2.

Comparative Example C6Ni₅Mg₂Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(12.35)O_(49.835)+50SiO₂

Reaction mixture A was prepared by heating 1619.7 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (1472.5 g) to form a clear colorless solution. Silica sot(27 ppm Na, 39 nm avg. particle size, 5357.1 g, 42 wt % silica) was thenadded with stirring.Reaction mixture B was prepared by heating 276.2 ml of deionized waterto 55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (608.6 g),Ni(NO₃)₂.6H₂0 (1216.8 g), Mg(NO₃)₂.6H₂O (429.2 g) and Cr(NO₃)₃.9H₂O(33.5 g).Reaction mixture C was prepared by heating 387.7 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (352.4 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 1009.4 g of 50 wt %aqueous (NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii) while the solutionwas stirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (182.7 g)and RbNO₃ (14.8 g) resulting in a clear orange solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry. Stirring of Reactionmixture F was continued for 15 minutes while the temperature wasmaintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating 3 hours in air at 290° C., 3 hours in airat 425° C. and then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst. Testing results are shown in Table 2.

Comparative Example C7Ni₄Mg₃Fe_(1.8)Rb_(0.192)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(12.386)O_(49.979)+50wt % SiO₂

Reaction mixture A was prepared by heating 181.5 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (165 g) to form a clear colorless solution. Silica sol(90 ppm Na, 39.2 nm avg. particle size, 606.8 g, 41.2 wt % silica) wasthen added with stirring.Reaction mixture B was prepared by heating 30.7 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (68.2 g),Ni(NO₃)₂.6H₂O (109.1 g), Mg(NO₃)₂.6H₂O (72.1 g) and Cr(NO₃)₃.9H₂O (3.8g).Reaction mixture C was prepared by heating 44.1 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (40.1 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 113.1 g of 50 wt %aqueous (NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii) while the solutionwas stirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (20.5 g) andRbNO₃ (2.7 g) resulting in a clear orange solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry. Stirring of Reactionmixture F was continued for 15 minutes while the temperature wasmaintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating 3 hours in air at 290° C., 3 hours in airat 425° C. and then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst. Testing results are shown in Table 2.

Example 3Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.539)+50wt % SiO₂

Reaction mixture A was prepared by heating 154.5 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (140.4 g) to form a clear colorless solution. Silica sol(27 ppm Na, 39 nm avg. particle size, 595.2 g, 42 wt % silica) was thenadded with stirring.Reaction mixture B was prepared by heating 26.5 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (32.2 g),Ni(NO₃)₂.6H₂0 (102.9 g), Mg(NO₃)₂.6H₂O (68 g) and to Cr(NO₃)₃.9H₂0 (1.8g).Reaction mixture C was prepared by heating 65.5 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (59.6 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 170.6 g of 50 wt %aqueous (NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii). while the solutionwas stirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (30.9 g) andRbNO₃ (2.5 g) resulting in a clear orange solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry. Stirring of Reactionmixture F was continued for 15 minutes while the temperature wasmaintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating 3 hours in air at 290° C., 3 hours in airat 425° C. and then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst. Testing results are shown in Table 2.

Example 4Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.335)O_(50.126)+50wt % SiO₂

Reaction mixture A was prepared by heating 149.9 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (136.3 g) to form a clear colorless solution. Silica sol(27 ppm Na, 39 nm avg. particle size, 595.2 g, 42 wt % silica) was thenadded with stirring.to Reaction mixture B was prepared by heating 27.1 ml of deionized waterto 55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (32.9 g),Ni(NO₃)₂.6H₂0 (105.4 g), Mg(NO₃)₂.6H₂O (69.7 g) and Cr(NO₃)₃.9H₂0 (1.8g).Reaction mixture C was prepared by heating 67.1 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (61 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 174.8 g of 50 wt %aqueous (NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii) while the solutionwas stirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (31.6 g) andRbNO₃ (2.6 g) resulting in a clear orange solution.Reaction mixture F was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry. Stirring of Reactionmixture F was continued for 15 minutes while the temperature wasmaintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating 3 hours in air at 290° C., 3 hours in airat 425° C. and then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst. Testing results are shown in Table 2.

Example 5Ni_(4.26)Mg_(3.195)Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.994)+50wt % SiO₂

Reaction mixture A was prepared by heating 152.9 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (139 g) to form a clear colorless solution. Silica sol(27 ppm Na, 39 nm avg. particle size, 595.2 g, 42 wt % silica) was thenadded with stirring.Reaction mixture B was prepared by heating 27.4 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (31.8 g),Ni(NO₃)₂.6H₂O (108.5 g), Mg(NO₃)₂.6H₂O (71.7 g) and Cr(NO₃)₃.9H₂O (1.8g).Reaction mixture C was prepared by heating 64.9 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (59 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 169 g of 50 wt % aqueous(NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii) while the solution wasstirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (30.6 g) andRbNO₃ (2.5 g) resulting in a clear orange solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry. Stirring of Reactionmixture F was continued for 15 minutes while the temperature wasmaintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating 3 hours in air at 290° C., 3 hours in airat 425° C. and then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst. Testing results are shown in Table 2.

Example 6Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.502)O_(50.627)+50wt % SiO₂

Reaction mixture A was prepared by heating 1363.6 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (1239.6 g) to form a clear colorless solution. Silica sol(90 ppm Na, 39 nm avg. particle size, 5461.2 g, 41.2 wt % silica) wasthen added with stirring.Reaction mixture B was prepared by heating 241.9 ml of deionized waterto 55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (293.9 g),Ni(NO₃)₂.6H₂O (940.2 g), Mg(NO₃)₂.6H₂O (621.8 g) and Cr(NO₃)₃.9H₂O (16.2g).Reaction mixture C was prepared by heating 599.1 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (544.6 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 1559.9 g of 50 wt %aqueous (NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii) while the solutionwas stirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (282.3 g)and RbNO₃ (22.9 g) resulting in a clear orange solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry. Stirring of Reactionmixture F was continued for 15 minutes while the temperature wasmaintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/145° C. The resulting powder wasdenitrified by heat treating 3 hours in air at 290° C., 3 hours in airat 425° C. and then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst. Testing results are shown in Table 2.

Example 7Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.539)+50wt %, 22 nm SiO₂

Reaction mixture A was prepared by heating 154.4 ml of deionized waterto 65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (140.4 g) to form a clear colorless solution. Silica sol(568 ppm Na, 22 nm avg. particle size, 625 g, 40 wt % silica) was thenadded with stirring.Reaction mixture B was prepared by heating 26.5 ml of deionized water to55° C. and then adding with stirring Fe(NO₃)₃.9H₂O (32.2 g),Ni(NO₃)₂.6H₂0 (102.9 g), Mg(NO₃)₂6H₂O (68 g) and Cr(NO₃)₃.9H₂O (1.8 g).Reaction mixture C was prepared by heating 65.5 ml of deionized water to65° C. and then adding with stirring over 30 minutes ammoniumheptamolybdate (59.6 g) to form a clear colorless solution.Reaction mixture D was prepared by (i) heating 170.6 g of 50 wt %aqueous (NH₄)₂Ce(NO₃)₆ solution to 55° C., and (ii) while the solutionwas stirring and heating, sequentially adding Bi(NO₃)₃.5H₂O (30.9 g) andRbNO₃ (2.5 g) resulting in a clear orange solution.Reaction mixture E was prepared by adding with stirring reaction mixtureB to reaction mixture A.Reaction mixture F was prepared by adding reaction mixture C to reactionmixture D. This resulted in precipitation of an orange solid. Theresulting mixture was the precipitate slurry.Stirring of Reaction mixture F was continued for 15 minutes while thetemperature was maintained in the 50-55° C. range.Reaction mixture F was then added to reaction mixture E to form thefinal catalyst precursor slurry.The catalyst precursor slurry was allowed to stir for one hour while itcooled to approximately 40° C. It was then homogenized in a blender for3 minutes at 5000 rpm. The slurry was then spray dried in a spray dryerat an inlet/outlet temperature of 325/140° C. The resulting powder wasdenitrified by heat treating 3 hours in air at 290° C., 3 hours in airat 425° C. and then calcined in air at 560° C. for 3 hours. Theresulting calcined powder was then tested as a propylene ammoxidationcatalyst. Testing results are shown in Table 2.

TABLE 2 % % % % Ex. X/Y C₃ ⁼ AN AN —CN No. Catalyst Ratio HOS Conv YieldSel Yield C3 Catalyst C49MC 0.35 87.0 C4Ni_(7.5)Mg₃Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(15.85)O_(63.835) +0.32 137 97.2 79.6 81.8 86.7 50 wt % 27 ppm Na, 39 nm SiO₂ C5Ni_(7.5)Mg₃Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(15.85)O_(63.835) +0.32 138 98.4 79.4 80.7 86.5 50 wt % 27 ppm Na, 39 nm SiO₂ C6Ni₅Mg₂Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(12.35)O_(49.835) +0.45 44 99.0 81.7 82.6 88.9 50 wt % 27 ppm Na, 39 nm SiO₂ C7Ni₄Mg₃Fe_(1.8)Rb_(0.192)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(12.386)O_(49.979) +0.51 142 99.0 83.6 84.5 89.9 50 wt % 90 ppm Na, 39.2 nm SiO₂ 3Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.539) +0.92 136 98.1 84.0 85.6 90.3 50 wt % 27 ppm Na, 39 nm SiO₂ 4Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.335)O_(50.126) +0.93 113 99.7 82.2 82.5 89.1 50 wt % 27 ppm Na, 39 nm SiO₂ 5Ni_(4.26)Mg_(3.195)Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.994) +0.85 142 98.6 82.4 83.6 89.2 50 wt % 27 ppm Na, 39 nm SiO₂ 6Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.502)O_(50.627) +0.97 138 98.2 83.2 84.8 89.7 50 wt % 90 ppm Na, 39.2 nm SiO₂ 7Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.539) +1.25 148 99.7 82.2 82.4 89.7 50 wt % 568 ppm Na, 22 nm SiO₂ Notes: 1.“X/Y Ratio” is the XRD intensity ratio X/Y as described herein. 2. “HOS”is “hours on stream. 3. “% C₃ ⁼ Conv” is mole percent per passconversion of propylene to all products. 4. “% AN Yield” is percentacrylonitrile yield. 5. “% AN Sel” is percent acrylonitrile selectivity.6. “% —CN Yield is combined percent yield of acrylonitrile, acetonitrileand hydrogen cyanide. 7. The catalysts of this invention are describedon an “Mo₁₂” basis (i.e. the subscript of Mo = 12), to convert any ofabove compositions to the “Mo₁₂” basis, simply divide each subscript inthe composition by the shown Mo subscript and then multiply by 12. Forexample, the Example 3 composition ofNi₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.539)is equivalent toNi_(3.748)Mg_(2.811)Fe_(0.843)Rb_(0.180)Cr_(0.047)Bi_(0.675)Ce_(1.65)Mo₁₂O_(48.295)on an Mo₁₂” basis.

TABLE 3 Ex. Ce/Fe Attrition No. Catalyst Ratio Test Losses C4Ni_(7.5)Mg₃Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(15.85)O_(63.835) +0.61 Not measured 50 wt % 27 ppm Na, 39 nm SiO₂ C5Ni_(7.5)Mg₃Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(15.85)O_(63.835) +0.61 Not measured 50 wt % 27 ppm Na, 39 nm SiO₂ C6Ni₅Mg₂Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(12.35)O_(49.835) +0.61 13.1 50 wt % 27 ppm Na, 39 nm SiO₂ C7Ni₄Mg₃Fe_(1.8)Rb_(0.192)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(12.386)O_(49.979) +0.61 10.3 50 wt % 90 ppm Na, 39.2 nm SiO₂ 3Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.539) +1.95 6.2 50 wt % 27 ppm Na, 39 nm SiO₂ 4Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.335)O_(50.126) +1.95 7.2 50 wt % 27 ppm Na, 39 nm SiO₂ 5Ni_(4.26)Mg_(3.195)Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.994) +1.95 6.1 50 wt % 27 ppm Na, 39 nm SiO₂ 6Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.502)O_(50.627) +1.95 7.1 50 wt % 90 ppm Na, 39.2 nm SiO₂ 7Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.539) +1.95 4.9 50 wt % 568 ppm Na, 22 nm SiO₂ Notes: 1. “Attrition TestLosses” is the result of a submerged jet attrition test and thenumerical value is the percent loss of catalyst for the period between 0and 20 hrs. This is a measure of overall catalyst particle strength.Lower attrition numbers are desirable. Attrition numbers above about 8.0are not preferred for commercial catalysts due to greater catalyst lossrate. The submerged jet is as described in the ASTM standard attritiontest.As can be seen from Tables 2 and 3, the catalyst compositions as definedby the instant invention (note the X/Y ratio) exhibit (i) higher overallto acrylonitrile, acetonitrile and HCN when propylene was ammoxidizedover such catalyst at elevated temperatures in the presence of ammoniaand air and (ii) lower attritions losses (greater particle strength),compared to similar catalysts outside the scope of the instantinvention.

Comparative Examples C8 and Examples 8-11

Various catalyst formulations were prepared by techniques as describedherein. For such formulations, Table 4, illustrates the catalysts withCe/Fe ratios less than about 0.7 have poorer attrition as opposed tocatalysts with higher Ce/Fe ratios.

TABLE 4 Attrition Ex. Results No. Catalyst Ce/Fe Ratio 0-20 hr C8Ni₅Mg₂Fe_(1.8)Rb_(0.12)Cr_(0.1)Bi_(0.45)Ce_(1.1)Mo_(12.35)O_(49.835) +0.611 12.82 50 wt % 27 ppm Na, 39 nm SiO₂ 8Ni₅Mg₂Fe_(0.9)Rb_(0.12)Cr_(0.05)Bi_(0.45)Ce_(1.1)Mo_(11.375)O_(45.485) +1.222 6.98 50 wt % 27 ppm Na, 39 nm SiO₂ 9Ni₄Mg₃Fe_(0.9)Rb_(0.192)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.806)O_(51.539) +1.956 6.32 50 wt % 27 ppm Na, 39 nm SiO₂ 10 Ni₄Mg₃Fe_(0.9)Rb_(0.18)Cr_(0.05)Bi_(0.58)Ce_(1.75)Mo_(12.575)O_(50.61) +1.944 6.35 50 wt % 27 ppm Na, 39 nm SiO₂ 11 Ni₄Mg₃Fe_(0.9)Rb_(0.12)Cr_(0.05)Bi_(0.72)Ce_(1.76)Mo_(12.77)O_(51.395) +1.956 7.60 50 wt % 27 ppm Na, 39 nm SiO₂

While the foregoing description and the above embodiments are typicalfor the practice of the instant invention, it is evident that manyalternatives, modifications, and variations will be apparent to thoseskilled in the art in light of this description. Accordingly, it isintended that all such alternatives, modifications and variations areembraced by and fall within the spirit and broad scope of the appendedclaims.

1-10. (canceled)
 11. A process for the conversion of an olefin selectedfrom the group consisting of propylene, isobutylene or mixtures thereof,to acrylonitrile, methacrylonitrile, and mixtures thereof, respectively,by reacting in the vapor phase at an elevated temperature and pressuresaid olefin with a molecular oxygen containing gas and ammonia in thepresence of a catalyst wherein the relative ratios of the elements insaid catalyst are represented by the following formula:Mo₁₂Bi_(a)Fe_(b)A_(c)D_(d)E_(e)F_(f)G_(g)Ce_(h)O_(x) wherein A is atleast one element selected from the group consisting of sodium,potassium, rubidium and cesium; and D is at least one element selectedfrom the group consisting of nickel, cobalt, manganese, zinc, magnesium,calcium, strontium, cadmium and barium; E is at least one elementselected from the group consisting of chromium, tungsten, boron,aluminum, gallium, indium, phosphorus, arsenic, antimony, vanadium andtellurium; F is at least one element selected from the group consistingof a rare earth element, titanium, zirconium, hafnium, niobium,tantalum, aluminum, gallium, indium, thallium, silicon, germanium, andlead; G is at least one element selected from the group consisting ofsilver, gold, ruthenium, rhodium, palladium, osmium, iridium, platinumand mercury; and a, b, c, d, e, f, g, h and n are, respectively, theatomic ratios of bismuth (Bi), iron (Fe), A, D, E, F, cerium (Ce) andoxygen (O), relative to 12 atoms of molybdenum (Mo), wherein a is from0.05 to 7, b is from 0.1 to 7, c is from 0.01 to 5, d is from 0.1 to 12,e is from 0 to 5, f is from 0 to 5, g is from 0 to 0.2, h is from 0.01to 5, and n is the number of oxygen atoms required to satisfy thevalence requirements of the other component elements present; wherein0.15≦(a+h)/d≦1 and 0.8≦h/b≦5, and wherein the X-ray diffraction patternof the above identified catalytic composition has X-ray diffractionpeaks at 2θ angle 28±0.3 degrees and 2θ angle 26.5±0.3 degrees, andwherein the ratio of the intensity of the most intense x-ray diffractionpeak within 2θ angle 28±0.3 degrees to the intensity of most intensex-ray diffraction peak within 2θ angle 26.5±0.3 degrees is defined asX/Y, and wherein X/Y is greater than or equal to 0.7.
 12. The process ofclaim 11, wherein 0.2≦(a+h)/d≦0.6.
 13. The process of claim 11, wherein0.3≦(a+h)/d≦0.5
 14. The process of claim 11, wherein 1≦h/b≦3.
 15. Theprocess of claim 11, wherein 1.5≦h/b≦2.
 16. The process of claim 1,wherein X/Y is greater than or equal to 0.80.
 17. The process of claim11, wherein X/Y is greater than or equal to 0.85.
 18. The process ofclaim 1, wherein the catalyst comprises a support selected from thegroup consisting of silica, alumina, zirconium, titania, or mixturesthereof.
 19. The process of claim 18, wherein the support comprisesbetween 30 and 70 weight percent of the catalyst.
 20. The process ofclaim 18, wherein the support comprises silica having an averagecolloidal particle size between about 4 nm and about 100 nm.